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Yellow 42Colored Paper |
People made paper to have something to write upon. Before the invention
of paper, ancient civilizations wrote on clay tablets, silk, and animal
skins. The first hand-made paper-like substance was made in the 4th century
BC out of papyrus, a native plant of the African marshes. Although papyrus
is not considered to be true paper, it was the first to share many similar
properties with present-day paper. 
(Hunter). Using the inner core of the stem,
people cut it into strips and laid layers of overlapping strips on boards.
Next they pressed the layers together and beat them with a hammer-like tool.
About the same time that Egyptians were making papyrus paper, Aztec and
Mayan Indians were making paper from the bark of fig trees. They had a similar
technique. After soaking the branch in water, they removed the outer bark;
then they worked strips of inner bark into a sheet formation. The Chinese
made paper from silk by first soaking the silk, then they beat it into a
pulp in water. They poured this pulp over a linen mat stretched on a frame
and let the fiber settle until it formed a sheet. This silk paper is considered
the birth of modern hand-made paper. In 105 AD Tsai Lun improved the silk
paper process by using a mat of fine bamboo strips, then he placed retaining
strips around the side of the frame to prevent pulp from running off. The
process of making paper moved to the Arab world in 751 AD when Chinese paper
makers were taken as prisoners of war. Hand-made paper surfaced in Europe
near Valencia, Spain, in 1144, where it eventually spread through central
Europe. Hand-made paper didn't show up in America until the end of the 17th
century. (Weidenmuller)
Making paper was tough work since men had to first build large vats,
mills, and presses of wood. Often they stood up all day bent over their
work "stations" forming sheet after sheet, one at a time. Each
sheet had to dry on a line or was pressed between cloth, which took time.
Many things were used as pulp, including tree bark, rags, hemp, rice straw,
and most recently, wood pulp. Although humans like to think of themselves
as the inventors of paper, wasps and hornets built nests from gray paper-like
material, making them the oldest paper makers in the world. (Weidenmuller)
There are essentially three types of pulp.
Raw pulp is material straight from nature that is untreated. In order to
use this type of pulp, the paper maker must cook the fiber in boiling water
in order to separate the plant and non-cellulose material from the 
cellulose, which
is the main ingredient in making paper. A second type of pulp is processed
pulp. It has already been cooked and partially beaten and is sold as a dry,
compressed sheet or as woven rags. The third type of pulp is called ready-to-use.
As you can guess from the name, it has been pre-beaten and is usually used
by people who have no access to a beater. (Dawson and Turner)
The Hollander beater was first used in
windmills before 1673. It consisted of an elongated tub with a track running
around the periphery. The main part is a rotating blade made from metal
alloys such as copper, brass, silver, or stainless steel. The blades are
mounted on a stationary bed plate. The more a stainless steel blade is used,
the smoother and rounder the edges become. This reduces the amount of cutting
of fibers, leaving fiber longer and well-fibrillated. Steel alloys tend
to wear down and develop sharp edges over time, which increases the amount
of cutting. As pulp passes under the rotating blades, it is abraded, and
the hydration process
occurs. (Aimsworth)
The beating process makes fibers soft
by unraveling fibrils
in the cellulose, then it works water into the intermolecular structure
through hydrogen bonding. (Dawson
and Turner) After fibers are beaten in a Hollander beater, the length
is cut, making them shorter, and the surface texture of the fiber is increased,
which aids in hydrogen bonding. Shorter fibers yield less supple and stronger
paper. A higher concentration of fiber increases the cutting of fibers,
and a lower concentration of fiber increases fibrillation, which yields
a denser, stronger, more translucent sheet of paper. (Toale). Hydrogen atoms are strongly attracted
to nitrogen atoms, oxygen atoms, and fluorine atoms. The positive hydrogen
ends of the water molecules attract the negative oxygen ends of other water
molecules. This explains why water molecules are so strongly attracted to
each other. Hydrogen bonds are quite strong and capable of holding molecules
together. (Clark)
Cotton linter is a vegetable fiber of
the fruit group. It comes from shorter fibers which cover the remaining
seeds after the staple cotton has been removed. The plant is "Gossypium".
Each fiber is a single elongated cell from the surface of the seed, which
ranges in length from 15-50 mm. The diameter of a fiber ranges from 15-22
mm. Cotton absorbs moisture well and is actually stronger when wet. Cotton
grows in a hot dry climate in countries such as USA, China, India, Egypt,
Africa, and others. (Sawbridge
and Ford). Abaca "Musa Textilis" is the Philippine
word for Manila hemp. It comes from the stalk of a plant that is related
to a banana plant. Fiber length is long. This fiber can be rehydrated in
a blender or beaten to produce a harder, stronger paper. Esparto "Lygeum
spartum" is another different fiber. It comes from the esparto grass
plants and was once used for rope, shoes, and baskets. It is a weaker, shorter
fiber that shrinks a little in the drying process. (Dawson and Turner)
Paper has several properties that are
important to consider when making paper. The thickness, or caliper, of paper
can be uniform or uneven. When making paper by hand, it can sometimes be
difficult to produce a sheet of paper with a uniform thickness. It is often
important to produce paper with tearing
resistance, since paper that tears easily is of little use to people
for writing, printing, or packaging. Paper may be opaque or transparent,
depending on the intended use of the finished product. Another important
property to consider is the resistance of paper to water. Paper that will
be around water, perhaps on poolside equipment, needs to be able to withstand
a little splashing. By adding specific amounts of different sizings, we
can alter the water resistance of paper. In any location paper tends to
attract moisture that is simply in the air, so all paper needs to have some
amount of resistance to water. Another factor to consider when making paper
is the cost balance. Certain materials will be more expensive than others,
and therefore, the paper maker must choose if the color of the paper is
more important than the strength of the paper, for example. (Aimsworth) Durability is another important property
of paper to consider. A paper maker will also want the finished paper to
exhibit permanence.
(Koretsky)
There are two materials that modern-day
paper makers use to color their paper. Dyes are added to raw pulp before
beating, and therefore become a part of the paper structure, actually coloring
the fibers. This is because they are soluble in water and penetrate the
fiber structure. Pigments yield a more permanent and even type of coloring
for paper. Because pigments are insoluble finely ground particles, adding
pigments alone to paper will not color the paper. Some sort of binder or
retention agent must first be added to the pulp before the pigment, which
will bind the pigment to the beaten fibers in the pulp. (Dawson and Turner). A retention
agent is a cationic
substance. It affects the electron conditions in the pulp and water
solution. (Toale).
The pigment should not contribute to the deterioration of the fiber; it
should only color it. It should also not rub off or bleed from the paper.
It might actually help to filter light from the environment, protecting
the paper. It takes less organic pigment to color paper than inorganic pigment
since there is a higher saturation, which is one reason why many people
choose an organic pigment over an inorganic one. The retention agent has
a neutral pH, and rinsing the pulp after coloring helps keep the pH of the
paper neutral. The pH
[of any liquid is the negative logarithm of the hydrogen ion concentration
in moles per liter.] The drawback in adding pigment and retention agents
is that the more additives in the paper, the weaker the paper becomes because
there are fewer hydrogen bonds. (Koretsky)
There are several hazards to consider
when making paper. If the fiber you intend to use comes from plants, then
there is the possibility that a person could have an allergic reaction or
skin irritation if the fiber is handled without gloves. Anytime a beater
is used, everyone should consider using earplugs to guard against hearing
damage, which usually is a hazard only when working in large mills around
many beaters all day long. People should take care not to place their hands
near certain parts of the beater where the blades rotate. Also, the beater
should always be disconnected from electricity when cleaning it or initially
filling it with water. (Dawson
and Turner)
Anytime pigments are used, people should
consider using gloves, a dust mask, goggles, or some type of barrier cream.
There are no significant hazards when using yellow 42. (Rossol)
Pigment yellow 42 is composed of hydrated
iron oxide and other iron compounds, and its pigment code is 77492. Other
names of this pigment in its natural form are ferrite yellow, Mars yellow,
and monohydrate of ferric oxide. In synthesized form it is known as ochre,
limonite, natural yellow oxide, African ochre, and Indian ochre. Iron oxides
are inorganic pigments widely used by artists because they are safe and
fairly indestructible. Their tint is fairly weak, and hues range from yellow
to brown to red to black. Iron oxide, Fe2O3, is fairly
inexpensive, which adds to its wide usage. (Koretsky) The wavelength of yellow ranges
from 560-590 nm. (Biermann)
I began by be
ating one pound of cotton linter for twelve
minutes in a David Reina beater [see pictures left]. I diluted one teaspoon
of pigment yellow 42 in one-hundred ml of water. Then I scooped 280 ml of
pulp in a beaker from my pulp sample, added fifteen drops of retention agent,
and stirred the mixture. Next I added fifteen drops of diluted yellow pigment
42 to the pulp and added enough water to the mixture to fill my container.
After I mixed the pigment with the pulp and retention agent, I poured the entire sample quickly into a floating mold and deckle, which I had floating in a large plastic container of tap water. I lifted the mold and deckle straight up from the water as soon as possible in order to obtain an even sheet of paper.
Next, I let the pulp sheet drain while I laid out my felts and placed Pelon on top of the felt. I sprinkled the Pelon with a little water which helps in the couching process. Then I couched the pulp sample onto the pelon and used blotter paper to help absorb some of the water. Finally, I laid my wet paper sheet on a board between blotter paper and felts to help absorb excess water and labeled this sheet sample A.
I repeated this entire process, starting with scooping a 280 ml pulp sample, twelve times. I added fifteen drops of retention agent and fifteen drops of pigment to my second sheet, which I labeled sample B. Samples C and D consisted of fifteen drops of retention agent and thirty drops of pigment. Samples E and F were also fifteen drops of retention agent and fifteen drops of pigment. Samples G and H were thirty drops of retention agent and fifteen drops of pigment. Samples I and J consisted of fifteen drops of retention agent and forty-five drops of pigment. Finally, samples K and L consisted of forty-five drops of retention agent and fifteen drops of pigment.
Table Key: RA = Retention Agent P = Pigment
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Sample A |
Sample B |
Sample C |
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Sample D |
Sample E |
Sample F |
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Sample G |
Sample H |
Sample I |
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Sample J |
Sample K |
Sample L |
My first test was to determine the pH level of the paper samples. I cut each sample (A-L) in half. Taking one paper section from each different ratio of retention agent to pigment, I wet the paper sample thoroughly, laid a pH indicator strip on the paper, then placed a heavy book on top of the paper for six minutes. Then I compared the pH strip color to the color chart to detemine if the paper was acidic, neutral, or alkaline. I also tested a sheet of white paper that I made for comparison.
My second test was to check for bleed fastness after the paper samples were dry. (The first bleed fastness test was observing the run off color from the wet pulp as it drained.) I cut twelve 1" x 3" strips of cotton linter and cut six of the paper samples, each one with a different ratio of retention agent to pigment, into 1" x 3" strips. Next I wet each of the homemade paper samples and placed them between two strips of white cotton linter. I then placed this sandwich between two glass slides and placed the final sandwich under a heavy book for ten minutes. Finally, I took the sandwiches apart and observed the white cotton linter strips for yellow coloring.
My third test was to discover how resistant my paper was to rubbing. I took a piece of printer paper and cut it into six sections. Next I selected six more of the paper samples as before, each having a different ratio of retention agent to pigment. Then I rubbed the printer paper onto the paper samples for about thirty seconds in a circular motion. Finally, I observed the paper.
My final test on my paper samples was with the colorimeter. I placed the measuring head on the remaining six samples of paper and got readings in the L*a*b* coordinate system.for the hue, value, and chroma of each paper sample. I recorded by readings from the colorimeter.
Throughout various stages of this experiment I had pictures taken.
When I stirred the pulp combined with retention agent and pigment, it resembled beating scrambled eggs. It was difficult to keep the mixture well-mixed. Once I poured the colored pulp into the mold and deckle, it settled quickly, making it difficult to make an even sheet of paper. Much color washed through the deckle as well as pulp. Also, each time I poured the pulp samples into the floating mold and deckle, the more pigment there was in the sample, the more color washed through into the larger container. During the couching, the water I pressed out of the paper was yellow, but did not color the pelon or blotter paper. The paper samples with thirty drops and forty-five drops of pigment were more saturated than the other samples. The edges of the paper were not defined, and a criss-cross pattern was formed on the paper from the screen in the mold and deckle. Also, the color was not completely uniform since there were darker lines along the edges on some sheets of paper. Samples I, J, K, and L were much stiffer than the others.
The white sample of paper had an acidic pH reading between five and six. This white paper was not as stiff as the colored paper I made. Samples B1 and D1 were weakly acidic with a pH reading a little less than seven. Samples F1, H1, J1, and L1 were all neutral with a reading of seven on the pH indicator scale.
With the bleed fastness test, the glass slides tended to slip around, and I had to be very careful when setting the heavy book on top of them so as not to crack them. On all of the samples, the white cotton linter was not discolored from the wet paper. (samples B2, D2, F2, H2, J2, and L2)
When rubbed with printer paper, little pieces of paper rubbed off sample A1, and the criss-cross pattern was abraded. Samples C1 and E1 were also abraded from the rubbing, but not as many pieces of paper rubbed off of them as A1. I almost made a hole in sample G1. Sample I1 was abraded, but there was little change in its pattern. I could hardly tell a change with sample K1. No color rubbed off of any sample apart from the color on the paper bits that rubbed off.
Colorimeter findings are as follows:
| sample | L* | a* | b* |
| A2 | 89.6 | -.93 | +20.4 |
| C2 | 85.9 | +.05 | +28.35 |
| E2 | 85.05 | -1.24 | +23.42 |
| G2 | 89.4 | -1.33 | +17.03 |
| I2 | 85.97 | +.02 | +27.11 |
| K2 | 89.02 | -.35 | +19 |
The constants in my experiment were the beater time, type of fiber, pulp sample size, pigment color, size of paper sheet, and type of retention agent. My variables were the amount of retention agent and the amount of pigment I used.
The retention aid did not help retain a lot of the color no matter how many drops I used. The stronger hues were the samples containing the most pigment. I believe the color was not uniform in the paper samples because the screen in the mold and deckle was warped. Perhaps the pigment in the colored pulp tended to settle in lower areas of the screen. The later samples were stiffer because they contained more additives (more drops of retention agent and pigment). The final dried paper was resistant to bleeding. I believe it was too hard to be uniform with the way I rubbed the paper samples and the amount of time I rubbed. Therefore, there is no correlation between the amount of pigment and amount of color that rubbed off.
The darkest and lightest readings from the colorimeter were both from the samples containing fifteen drops of rention agent and fifteen pigment drops. The value readings do not seem to have a correlation with retention agent amounts or pigment amounts. Positive a* readings indicate the hue tends toward red, and negative hue readings indicate the hue tends toward green. The two samples with thirty drops and forty-five drops of pigment have the positive readings. Positive b* readings indicate the samples tend toward yellow, and negative chroma readings indicate the samples tend toward blue. Obviously, since yellow pigment was used, all the readings are positive. The two samples with the highest chroma readings were, not surprisingly, the samples with thirty and forty drops of pigment. This was because these two samples were more saturated.
Originally I had planned on making thirty-two sheets of paper and comparing four different things. I was going to do my same pH level test, bleed test, rub test, and colorimeter reading on paper containing a small amount of pigment, maybe 2 drops. Then I was going to do the same tests on paper containing a larger amount of pigment such as forty drops. Next I was going to make paper from two different fibers, cotton linter and abaca. I planned on running the four tests mentioned above on these samples, and then I would make observations. My third comparison was going to be between paper containing a retention agent and paper containing sizing instead. My final comparison was to make paper using a dry version of pigment and paper using an aqueous solution of the same pigment. I did not end up making all of these comparisons because there was not enough time. They might be interesting areas to pursue.
I suggest that anyone trying to make colored paper make some sample sheets of white paper first. Also, you should play around with your coloring to decide how saturated you want your final paper. I would also suggest not using a retention agent since it had no effect on binding pigment to the color in paper fibers. It is probably just a way for companies to make money. Make sure that your pulp and retention agent is mixed together as best you can, then add the pigment and mix it in well also. The sooner you pour the colored pulp into the mold and deckle, the less time there is for the pigment to settle to the bottom. Also, I recommend using Pelons that are white and have no dirt particles on them. If you use dirty Pelons, then chances are you may have some of the color or dirt dry on to the paper.
For anyone interested in pursuing more experiments in the area of colored paper, I would suggest making white paper of the same fiber as the colored paper. This way you can run comparisons with the white versus the colored paper. Another idea would be to make colored paper from two different fibers. Then you can see if different fibers bleed color or withstand rubbing the same. Another idea would be to use an aqueous pigment to make colored paper, and then use the same pigment in dry powder form to make more colored paper. It would be interesting to see if the different types of pigment affect the pH level, the bleeding, the rub fastness, or the reading on the colorimeter. All of these comparisons are the tests I planned to do but did not have time for. One other possible comparison would be to try one inorganic pigment and one organic pigment, then observe the differences in the paper. There are many different types of tests to run on paper for testing endurance, strength, etc. You may be able to find ideas about other tests on the links below or in books from the library.
Aimsworth, John H., Paper: The Fifth Wonder, Thomas Publishing Co., Kaukauna, Wisconsin, 1958.
Biermann, Christopher J., Handbook of Pulping and Papermaking, 2nd ed., Academic Press, San Diego, 1996.
Hunter, Dard, Papermaking: The History and Technique of an Ancient Craft, Dover Publications Inc., New York, 1947.
Koretsky, Elaine, Color for the Hand Papermaker Part 1, Carriage House Press, 1983.
Sawbridge, Maureen and Ford, John E., Textile Fibres Under the Microscope, Shirley Institute, 1987.
Toale, Bernard, The Art of Papermaking, Davis Publications, Inc., Worcester, Massachusetts, 1983.
Weidenmuller, Ralf, Papermaking: The Art and Craft of Handmade Paper, Thorfinn International Marketing Consultants Inc., San Diego, 1984.
Amanda Spann, 1998.